Starting problem

I have a 03' 4.0 When I start it up for the first time or after its been sitting for hours, it starts right up. If I go to multiple stores and it sits 5-10 mins in between each of them it has issues starting. The first time the car will crank a sec or 2 then starts. Each time I stop it cranks longer before it kicks over. On hot days after the 3rd or 4th time the truck will not start until it cools completely down. (hrs) I believe its a fuel issue because after a no start, I sprayed starter in the throttle body and it fired right over. Fuel pump was already replaced. Any help would be appreciated.

I wonder if you could start with replacing the fuel filter. My first car would only start if it had been sitting overnight, replaced fuel pump, same problem, replaced carb, same problem, finally found the fuel filter along the frame and replaced that and WOW!!! Blew through the new filter and it was like blowing through a straw into the air, blew through the old filter and it was like blowing into a milkshake.

Did the '03 have a return fuel regulator? If so it could be fuel regulator problem. My '04 has a pulse type fuel pressure with a fuel rail pressure sensor. My pressure sensor was failing before I ever got a code.

Also you might try cleaning the contacts on the pump relay or replacing it. The coil might be over heating. There fore no problem after cool down.

This is just some idea's. Not saying it is the problem.

A nieghbor had a relay issue with his older F-150. He replaced the relay and problem like yours was fixed.